W. Burger

Design and development process of a humanoid robot upper body through experimentation

The development of a humanoid robot within the scope of the collaborative research centre 588 has the objective of creating a machine that closely cooperates with humans. This development area presents a new challenge to designers. In contrast to industrial robots - for which mechanical rigidity, precision and high velocities are primary requirements - the key aspects here are a lightweight construction, prevention of hazards to users, and a motion space that corresponds to that of human beings. In order to meet these requirements, the robot must have manlike appearance, motion spaces and dexterity. Additionally, its kinematics should be familiar to the user, its motions predictable, so as to encourage inexperienced persons to interact with the machine. The design of the body of a mechatronical robot, which is intended to imitate the mechanical and sensory properties of humans, can only be realized in an intense iterative process. This article gives insight into the development processes of exemplary mechanical constructions, presently worked on at the University of Karlsruhe (TH). The design of single body parts and their improvement are presented. Details - why these improvements lead to a higher performance of the complete system - are discussed. This is a status report on current development in this area.

Acoustic Emission Analysis for Monitoring of Tribological Systems

Today, for the monitoring of hydrodynamic bearings, a multitude of measurement systems is available, of which however none has yet prevailed in practice. A practicable and effective principle to detect first rubbing processes in nonstationary charged sliding contacts is still missing. E. g., a failing bearing in a ship’s engine may lead to the threat of machine, ship and environment as far as to human lives, and certainly to high repairing costs and downtime. Failure-free running machinery demands efficient and reliable monitoring systems which make possible to evaluate the current condition of the bearing arrangement in operation.Copyright

BioMotionBot: a new 3d robotic manipulandum with end-point force control

In this paper we present the design of a new 3D robotic manipulandum that will be used in human motor-control research and additionally enables physiotherapists to design tailor-made robotic therapies. Moreover, it offers the opportunity to develop completely new types of movement-specific coordination and condition training programs in sports. The presented manipulandum has a special designed 3D kinematics that allows movements in 3D space while maintaining its orientation. The paper contains an overview of the mechanical design, the electronic components, the user interface, the design of the control system as well as a first performance test.

An Approach for the Modularization of a Product Architecture of Redesign Processes of Complex Systems

Design Structure Matrix (DSM) is known as an efficient tool to modularize product architectures. It is only effective when all the matrix elements are described with a similar level of abstraction. This lies generally in the level of the real existing components. In order to implement a DSM, all assemblies, components and their relations have to be defined beforehand. In this step, the product architecture is often developed intuitively without any analysis. After the analysis using DSM, the developed product architecture normally requires rectification. Some components have to be designed and modified repeatedly. In this paper, the model for describing the relationship between function and embodiment, the Contact and Channel Model (C&CM) as well as an approach and its implementation will be presented to avoid this repetition. After a principle solution has been selected, the system is modeled with C&CM elements in a new intermediate level of abstraction. An integration analysis by DSM can be performed in parallel with the use of a search algorithm to find the modular product architecture. The analysis result is a guideline for a modular architecture which helps designers to reduce the number of required iterations. This approach is implemented in the development of a robot forearm for the humanoid robot ARMAR III.Copyright

Energy Efficient Hydrodynamic Journal Bearings by Means of Closed-Loop Controlled Lubrication Flow

State of the art of hydrodynamic journal bearing lubrication is realized by a significant oversupply with lubricant, causing energy losses due to fluid film friction in the unloaded areas of the bearing. Reducing the lubricant flow however may lead to overheating or collapse of the load carrying fluid film, both resulting in a complete failure of the journal bearing. A new approach to safely reduce the lubricant flow is presented in this paper, by using a broadband piezoelectric acoustic emission sensor to detect ultrasonic structure-borne noise, usually caused by metal-to-metal contact at boundary conditions. The method of structure-borne noise analysis has proven to be suitable for detecting the occurrence of solid friction [1–4]. By combining structure-borne noise analysis with a closed loop control of a proportional flow control valve a condition dependent lubricant flow can be set. Thus lubricant friction in the bearing is reduced and additionally electrical energy in the peripheral devices, such as pumps can be saved.Copyright

Condition-Monitoring Based on Structure-borne Ultrasound Analysis

Recent results in condition monitoring of machine elements by acoustic emission analysis are presented. A special method based on the evaluation of structure-borne noise emissions in the ultrasonic range is described. The ultrasound-signals caused by friction processes are captured by a broadband piezoelectric sensor and analyzed subsequently. The method has proven to be suitable for detecting the occurrence of friction between solid objects in a very reliable way. This leads to a variety of possible applications wherever occurrence of solid body friction has to be considered as an indication of failure or wear. In addition to tribometer tests, experiments with sliding bearings and slide ring seals are presented exemplarily. In both cases promising results were achieved. The significant difference of the presented method compared to other sound-based methods is in the nature of the analyzed signals: Harmonic waves of audible sounds or percussion-type stimulations are not evaluated but the portion of friction sounds emerging in the ultra-sonic range beyond audible frequencies. These friction sounds are widely unaffected by ambient noise and other sources of interference.Copyright

A New Test-Bench for Study of Plain Bearings Under Mixed Lubrication

The experimental knowledge about medium lubricated journal bearings (e.g. diesel-oil lubricated sliding bearings in fuel-injection systems) is far too small in order to confirm the different hypotheses of the actual simulation models. The study of such components implicates very restrictive requirements on security against explosion, exact measurement of the friction torque and so on. A new test bench design to meet these requirements is presented, allowing a system-conform study of the components. For a high resolution of the temperature repartition in the smearing gap, thin film sensors, which have allowed the verifications experiments in the field of the Elastohydrodynamic-lubrication (EHL) are being enhanced. Beside a higher wear resistance, a reduction of the sensor size is an important requirement for the new sensor generation, allowing the resolution of local phenomena in the mixed lubrication. For the electrical isolation and wear protection of the new sensors developed at the Institute of Product Development of the University of Karlsruhe (TH) (IPEK), diamond like carbon (DLC) coatings are used. For the fulfillment of the requirements on the size of the sensors, a new concept of micro thermocouples is presented.Copyright

Maßnahmen zur Begrenzung der latenten Betriebsgefahr von großen Dieselmotoren (über 2,25 MW) auf Schiffen Teil 2

In Teil 1 [7] der Abhandlung der Schaller Automation wurde herausgestellt, dass es zu diesem Thema international geregelte Sicherheitsvorschriften gibt, die aber nicht eindeutig sind und deren Durchsetzung problematisch ist, weil genaue technische, verifizierbare Vorschriften nicht verfugbar sind. Teil II erlautert das Bestreben der Schaller Automation, einen Beitrag dahingehend zu leisten, die zur Sicherheit getroffenen, grundsatzlichen Masnahmen praktisch realisierbar und auf ihre Effizienz hin uberprufbar zu machen, ohne dass sicherheitsmindernde Zugestandnisse wie: „... where practicable ...“ [8] erforderlich werden. Um eine Grundlage fur dieses Bestreben zu schaffen, wurden Versuche und umfangreiche Messungen insbesondere am Institut fur Maschinenkonstruktionslehre und Kraftfahrzeugbau der Universitat Karlsruhe (TH) unter Leitung von Prof. Dr. A. Albers durchgefuhrt. Ein Resumee daraus zeigt, dass eine Verbesserung der Motorschutzmasnahmen durchaus moglich ist, so dass auch im Hinblick auf deren kontrollierte Anwendung Fortschritte erzielbar sind.